This invention relates to a sheltering device, and more particularly pertains to a cover designed to operate effectively in preventing any leakage around a vent pipe and through its flashing even though significant disparity exists between the coefficient of expansions for the vent pipe and its accompanying and surrounding flashing.
Customarily, in the plumbing trade, and usual type of cast iron vent pipe extends upwardly through the roof of the building, and then a flashing, usually also constructed of some form of metal, such as lead, is provided for mounting upon the roof of a building, with the upper end of this type of standard flashing having an extending lead sleeve that is usually peened over by means of hammering or other bending and into the upper end of the cast iron vent pipe, thereby sealing the opening in the roof through which the vent pipe extends. This prior art type of flashing for the vent pipe has generally worked satisfactory, primarily because the various types of metals from which both the vent pipe and the flashing have been constructed are metals both having a very low, or somewhat equivalent, coefficient of expansion. But, over the past few years, there has generally been developing a market for the plastic type of piping that is now being frequently used in the plumbing industry, generally such piping being constructed from a polyvinyl chloride, or a compound of acrylonitrile-butadiene-styrene copolymers, generally identified in the trade as ABS. And, while this type of piping, thus far, has been found to work very effectively for plumbing installations, such pipe has a reasonably high coefficient of expansion which makes it very different to provide closure around the vent pipe when formed of one of these materials particularly where it extends through the building roof. For example, these vent pipes extend through a hole or aperture in the roof of the structure, and then have the old style of flashing, namely, one having an upper sleeve of lead, and which is sealed in place upon the roof, with said lead sleeve being peened over and around the upper edge of the plastic pipe. Then, and as frequently occurs, particularly in cold weather where the upper end of the plastic vent pipe may be exposed to very low winter temperatures, and with the vent pipe located within the building being exposed to the heated environment of the interior of the building, generally in the vicinity of 65.degree. to 75.degree. F., such has caused a high expansion of the plastic pipe. As a result, such a vent pipe expands considerably, while the lead flashing remains rather static, and with the only location for expansion of the vent pipe being in an upward shifting direction through the roof of a building, since usually its lower end is reasonably fixed to other plumbing installations, there is, therefore, no room for expansion downwardly. Consequently, the metal type flashing surrounding the upper end of the vent pipe is frequently broken loose and clear from its mounting upon the roof, causing a wide open gap in which the rain or other elements may easily flow as through the hole provided in the roof of the structure, and through which the vent pipe extends, eventually causing severe damage to the structure roof of the building within the vicinity of its said vent pipe.
As an example of the type of expansion problems encountered in forming vent pipes of the newer plastic type materials, it has been found that a vent pipe formed of polyvinyl chloride, and having a length approximating 35 feet when initially prepared for use, will expand as much as 7/8 inch when exposed to temperatures in the range of 140.degree. F., while at the same time, when exposed to temperatures in the vicinity of 33.degree. F., may contract as much as 1/2 inch. In addition, a pipe formed from ABS, and also having an initially and precisely cut length of approximately 35 feet, will expand well over 11/2 inches when exposed to temperatures in the vicinity of 140.degree. F., and will contract as much as 1 inch when exposed to temperatures, as at the other extreme, around 35.degree. F. Bear in mind that the temperatures selected for these tests are not too unsimilar to the temperatures normally encountered by that portion of a vent pipe that extends through the roof of a structure, since in the hot summer sun, temperatures may well reach in the vicinity of 140.degree. F., at the roof line, while in the wintertime, temperatures within the central and northern parts of the United States easily average 33.degree. F. And, expansions of the type previously identified, particularly under summer heat, and even when the pipe interiorly of the structure, where most of it is located, is exposed to temperatures in the vicinity of 70.degree. F., when they expand the 1 inch or more in length, does have a very detrimental effect upon the lead flashing which had previously been peened around the upper edge of the pipe when installed. Thus, and particularly when expansion occurs, there is no place for the lead flashing to move but up, and when this occurs, it normally breaks loose from its mounting upon the roof structure, thereby readily exposing the gap between the roof and the enclosed vent pipe to rain, snow, or any other elements that eventually flow upon the surface of the roof.
The current invention is designed for use with the present lead roof flashing which is predominantly used in the trade, and at the same time, totally eliminates any leakage that occurs from the problems now associated with the usage of plastic pipe with such a lead flashing, since the problem of expansion and contraction has been alleviated through the structure of this invention.
Various prior art patents have given some consideration to the fabrication of shields for use in conjunction with roof vent pipes. For example, in the U.S. Pat. No. 3,797,181 to Nievelt, there is disclosed an outer cylindrical sheet that extends downwardly for flaring into an overlapping fashion and resting upon its modified form of sheet metal base, as shown. There are two significant differences between the shield of this prior art patent, and the current invention, in that the shield as shown is not fixed to any particular structure, but rather, simply rests upon the flashing. And, the shield is drapped over the vent pipe, and therefore, does not move with its expansion, as does the current invention.
The U.S. Pat. No. 1,010,100, to Wallace discloses a roof jacket for a ventilating pipe, wherein a sleeve is provided upon the top edge of the vent pipe 4, and then has another sleeve disposed for telescoping about the vertical pipe portion of the flashing. The cap of this jacket contains a series of interconnecting lugs that are designed for passing through various notches formed upon the pipe so that the cap may be rotated so as to lock it in place. And, a disc and stud are further provided for partially enclosing the center of the vent pipe as shown, and therefore, actually obstruct, rather than allow, the free flow of air out of the vent pipe. The patent is specifically upon an adjustable ice and frost proof flashing, its base having adjustability to compensate for varying slopes on roofs, and since no plastic pipe was available in 1911, Wallace had no concern with expansion matters. And, for this reason, this prior art patent shows its pipe 10 and section 9 in contiguity, unlike the present invention.
In any event, the structure of this Wallace jacket, particularly at its upper reaches, is quite dissimilar from the rather easily assembled adapter as designed and shown in the current invention. And, whereas Wallace is designed having contact between its sleeve and its pipe, the current invention avoids such.
Other prior art patents in this particular field include a U.S. Pat. No. 1,750,019 to Moore, the U.S. Pat. No. 1,923,220 to Lightbown, U.S. Pat. No. 2,307,269 to Hauser, and the U.S. Pat. No. 3,436,880 to Kiefer.
In view of the foregoing, it is, therefore, the principal object of this invention to provide a no leak expansion vent cover for use in conjunction with a current flashing provided upon the roof of a building structure.
Another object of this invention is to provide a vent cover which may be made in various sizes to be readily connected onto existing vent pipes and cooperate with the flashing so as to overcome problems associated with material expansion as currently exists.
A further object of this invention is to provide a vent cover which prevents lead flashings from being torn loose from their mountings upon roof structures.
An additional object of this invention is to provide a vent cover that allows for free expansion of the plastic vent stack or pipe, without any contact or cooperation needed for its functioning from the surrounding flashing, which will remain in a fixed position.
Another object of this invention is to provide a vent cover that is highly successful in operation and has received approved usage where ever installed.
Yet another object of this invention is to provide a vent cover that can be easily modified, at the job site, for mounting upon plastic vent pipes of a variety of sizes.
A further significant attribute of this invention is to provide a vent cover that allows for the full inside diameter of the vent pipe to vent its gases to the atmosphere.
A further object of this invention is to provide a vent cover that can be easily installed upon new construction, or modified in repair of existing vent structures, within a matter of minutes.
These and other objects will become more apparent to those skilled in the art upon reviewing the summary of this invention, and upon undertaking a study of the description of its preferred embodiment, in view of its drawings.